1. Field of the Invention
This invention relates to a sample analyzing apparatus and more particularly to such a sample analyzing apparatus as a scanning electron microscope (referred to as "SEM") equipped with energy diffusion type X-ray analyzer (referred to as "EDX") and a laser mass spectrometer.
2. Description of the Related Art
A typical application field of the present invention is semiconductor production. In semiconductor production, the particle on wafer is one of the largest causes for determining product yield. To make a countermeasure for reduction of adhering particles and carry out it, it is necessary to find a generation source of the particles To find out the generation source of the particles, obtaining information of particle composition is an effective weapon. For the particle composition analysis, SEMs with Energy Dispersive X-ray Spectroscopy analysis capability has been widely used. When the composition analysis on the particle on the wafer is carried out by SEMs with Energy Dispersive X-ray Spectroscopy analysis capability, for example, following processes are carried out.
A wafer to be measured taken out of a wafer cassette is pre-aligned with reference to an orientation flat or notch of the wafer. The pre-alignment is an operation of aligning a crystal direction of the wafer with a traveling direction of the XY stage. After the pre-alignment is performed, the wafer is carried to the XY stage in a sample chamber kept in vacuum condition and mounted thereon. The wafer mounted on the XY stage is aligned by means of an optical microscope mounted on a top face of the sample chamber. The alignment is an operation for correction between the coordinate systems of a pattern formed on the wafer and stage coordinate systems. Concretely, an optical microscope image magnified several hundreds times of the alignment pattern formed on the wafer is compared to a reference image of the alignment pattern preliminarily registered, and stage position coordinates are adjusted so that that magnified optical microscope image overlaps the reference image. After the alignment, the wafer is moved to a particle to be analyzed. After the wafer is moved to the particle position, electron beam is irradiated thereover and X-ray spectrum is formed and displayed. By observing the X-ray spectrum, an observer determines and identifies the composition of the particle with reference to knowledge and information possessed by him.
However, according to such a method, if the operator is not an expert, a standard of determining the composition becomes obscure, so that a result of identification is not reliable, and further it takes long to analyze.